1. Drive roller diameter.
When the conveyor belt bypasses the drum, bending stress is generated, causing the core to fatigue. The smaller the diameter, the greater the bending stress. Obviously, increasing the diameter of the drum is beneficial to increase the service life of the conveyor belt. However, when the value is increased to a certain value, the bending stress is not significantly reduced, and the volume of the equipment is increased. Therefore, in order to ensure that the bending stress of the conveyor belt is not too large, the minimum diameter of the drum should be limited. The principle of selecting the diameter D of the driving roller is: D≥100i, mm (i is the number of canvas layers) when the multi-layer core conveyor belt adopts the mechanical joint; when the vulcanized joint is used, the joint is a trapezoidal joint, which is easy to be under the bending stress Peel off, so D ≥ 125i, mm. When using a mechanical joint for the integrated core conveyor belt, D ≥ K8, mm (k depends on the parameters of the core frame material; 8 is the core thickness, mm). When using a steel cord conveyor belt, D = (150 ~ 200) (t, mm (d is the diameter of the wire rope, mm). The diameter of the reversing drum is based on the diameter of the driving drum, the percentage of force applied, and the angle of the conveyor belt to the drum wrap angle. Ok.
2, the roller is in the groove angle.
The load-bearing branch usually adopts a trough-shaped idler set composed of three-section idler, and the angle between the side roll and the middle roll is called a groove angle. Within a certain limit, the larger the groove angle, the larger the material flow rate. However, when the groove angle exceeds the groove forming capacity of the conveyor belt itself, the conveyor belt will not abut the middle roller during the no-load operation, thereby causing strong wear and unstable operation of the belt edge; during heavy load operation, the conveyor belt A large bending stress is inevitably generated at the corners of the side idler and the middle idler, causing longitudinal breakage of the conveyor belt or rapid peeling of the canvas layer. Therefore, it is required that the groove angle of the roller must be consistent with the groove forming ability of the selected conveyor belt. This principle should also be observed when replacing the new conveyor belt in use. Usually, the idler has a groove angle of 30. When the conveyor belt has good groove performance, it can be increased to 35.
3. Excessive distance.
The section of the conveyor belt between the head and tail rollers of the conveyor and the first set of carrier rollers is referred to as a transition section. In the transition section, the conveyor belt is changed from a groove shape to a parallel shape or a parallel shape to a groove shape, and the belt edge is stretched to generate an additional tensile stress. The smaller the length of the excess section, the greater the tensile stress, which causes severe wear on the edge of the conveyor belt and the side rollers, whereby the conveyor belt prematurely exhibits fatigue and even causes the edge of the conveyor belt to break. In order to locally extend the edge of the conveyor belt beyond the elongation of the conveyor belt, the length of the transition section should not be too small. For the fiber core conveyor belt, the length of the transition section is taken as 1.3 times the spacing of the idler; since the allowable elongation of the steel cord conveyor belt is 0.2%, the length of the transition section is calculated according to the formula L ≥ 2.67 cc B, where B is the bandwidth , m; d is the groove angle of the roller, rad. If the L value is much larger than the load roller spacing, several transition roller sets with a smaller groove angle order should be installed between the drum and the first set of carrier rollers to prevent drooping and sprinkling.
4, the radius of the convex arc.
When there is a convex arc segment on the conveyor line, there is also a large tensile stress at the edge of the conveyor belt, which causes the conveyor belt and the roller to break prematurely, so the radius of the convex arc segment should not be too small. When using a steel cord conveyor belt, the radius of the convex arc should be not less than (75~
5, feeding device.
Whether the structure of the feeding device is reasonable or not determines the service life of the conveyor belt to a large extent. In order to reduce the wear and impact stress of the material on the conveyor belt, the technical requirement f-1 of the design of the feeding device is: the speed and direction of the material to the conveyor belt should be approximately the same as the belt speed; minimize the drop of the material. In particular, it is necessary to prevent large pieces of material from falling directly onto the conveyor belt from a high place; in the interior of the feeding device, the material should be formed into a free continuous stream, and the material can be uniformly loaded into the middle of the conveyor belt in the correct shape, not allowed. There are material accumulation and sprinkling; as soon as possible, the powder and fine pieces are discharged onto the conveyor belt to form a cushion layer, and then the block material is loaded. A buffer roller set should also be provided at the loading point to reduce the impact of the material on the conveyor belt. The installation position of the feeding funnel must ensure that the material falls between the two sets of buffer roller sets instead of falling into a certain group of buffers. On the roller.
6, conveyor start and brake mode.
In the process of starting and braking, the belt conveyor should use the soft start mode to control the acceleration and deceleration during parking to reduce the dynamic stress. For general small and medium-sized belt conveyors, it is more reasonable to use a torque-limiting fluid coupling to achieve soft start. For long-distance, large-capacity large belt conveyors, due to the large dynamic tension, a controllable soft starter should be used to extend the start and brake time and reduce the dynamic stress. Commonly used controllable soft start devices are speed-regulating hydraulic couplings, CST controllable drives and variable frequency withering devices